Under the Old City of Zagreb (Capital of Croatia) lies a system of tunnels made in past. Even today nobody (not even cavers) knows the position of every channel in this cave system, since it is forbidden to come inside the unstable channels under the old city. At Isle of Pag in the town Novalja there is an artificial cave called Talianova Buza. This is an ancient Roman water supply pipe, more than 1050 meters long. The longest artificial caves in Croatia are located in the city of Pula. There are plenty of ancient tunnels and also some underground quartz sand mines. This system is longer than 15 km. Near the city of Drnis an ancient mine of aluminium can be found, with depth greater than 300 meters and length of several kilometers. Near the city of Omis there is an ancient marl mine, more than 2 kilometers long, with two vertical and one horizontal entrance.